Transient voltage surge suppression module with ultrafast fusing

Abstract

A transient voltage surge suppressor (100) for use in a single or poly-phase power distribution network to protect equipment supplied power from the network from damage caused by line surges or transients. A plurality of surge suppression assemblies (102A-102G) each of which includes a plurality of semiconductors (114) connected in parallel and a fuse wire (118) connected in series with each semiconductor. Each assembly is mounted on a separate circuit board (126A-126G). A fault detection circuit (104) in each assembly includes both a sensor (132A-132G) for sensing when a semiconductor in one of the surge suppression assemblies fails, or when a fuse wire in one of the assemblies clears, and a circuit (152) for providing a visual indication thereof. The fault detector is mounted on a separate circuit board (131). The respective circuit boards are installed in a module (120) with the one set of circuit boards on which the surge suppression assemblies are mounted being installed in one plane, and the circuit board on which the fault detector is mounted being installed perpendicular to them. A plasma suppression medium includes a sand and epoxy material for preventing spread of a plasma produced when a semiconductor fails or a fuse wire clears. The sand and epoxy material fill the module including the spaces between the circuit boards to prevent the spread of any plasma created due to semiconductor failure or fuse wire clearing.

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is: 
     
       1. Transient voltage surge suppressor (TVSS) apparatus for connection to a power line to protect equipment connected to the line from damage in the event of high voltage surges or transients comprising: semiconductor means connected to the power line, said semiconductor means being normally non-conducting when normal line voltage is supplied thereto, but being switched into conduction by the voltage provided thereto when an overvoltage condition caused by a line surge occurs;   fuse means connected to the semiconductor means to protect the semiconductor means in the event of an excessive current spike caused by a high voltage transient on the line;   module means in which said semiconductor means and said fuse means are installed; and,   plasma suppression means substantially completely filling said module means for preventing the spread of a plasma produced if the semiconductor means or the fuse means is destroyed by the line surge or transient, said suppression means including means substantially completely encapsulating both the semiconductor means and fuse means within said module means so plasma produced if either the semiconductor means or fuse means fails is quickly extinguished and thus cannot spread to other components.   
     
     
       2. The apparatus of claim 1 for use in a single or poly-phase power distribution network wherein the apparatus includes a plurality of surge suppression assemblies with each separate surge suppression assembly including said semiconductor means and fuse means connected between each "phase" of a poly-phase distribution network and said module means includes a module cover in which all of the surge suppression assemblies are housed. 
     
     
       3. The apparatus of claim 2 wherein the semiconductor means of each suppression assembly includes a plurality of semiconductors connected in parallel between each of the "phases" and the fuse means includes a fuse wire connected in series with each semiconductor. 
     
     
       4. The apparatus of claim 3 wherein the semiconductors and their associated fuse wires for each suppression assembly are commonly mounted on a circuit board. 
     
     
       5. The apparatus of claim 4 wherein all the circuit boards for the respective suppression assemblies are commonly installed in the module cover. 
     
     
       6. The apparatus of claim 5 wherein respective pairs of circuit boards are installed in the module cover facing each other, and the plasma suppression means includes material means substantially completely filling the spaces between the circuit boards. 
     
     
       7. The apparatus of claim 6 wherein the material means is a clean silica sand of tyler sieve size -60+200 or, other similar packing materials. 
     
     
       8. The apparatus of claim 6 wherein the material means includes a sand, the module cover being filled with a first layer of sand prior to installation of the circuit boards in the module, and to a second and higher level after the boards are installed, the second layer of sand to which the module cover is filled, substantially covering the installed circuit boards. 
     
     
       9. The apparatus of claim 7 further including means for sensing when a semiconductor is destroyed or a fuse wire blows, and means for providing a visual indication thereof. 
     
     
       10. The apparatus of claim 9 wherein the sensing means and visual indication means are commonly mounted on a circuit board, said circuit board being installed in said module cover after said cover is filled with sand. 
     
     
       11. The apparatus of claim 10 in which said plasma suppression means further includes an epoxy material with which said module cover is filled after the circuit board on which said sensing means and said visual indication means are mounted is installed in said module cover. 
     
     
       12. The apparatus of claim 11 wherein the epoxy material is an Insulcast 116 FR Part A/B and Insulcast 116 FR Part A/B FC or, other similar material. 
     
     
       13. The apparatus of claim 11 wherein the fuse wires are made of silver wire. 
     
     
       14. The apparatus of claim 10 wherein the sensing means includes an opto-isolator connected to each surge suppression assembly, the opto-isolator being switched from one operating state to another when a semiconductor in the associated suppression assembly is destroyed or a fuse wire in the assembly is blown. 
     
     
       15. The apparatus of claim 3 wherein said semiconductors are metal-oxide varistors. 
     
     
       16. The apparatus of claim 3 further including means for sensing when a semiconductor is destroyed or a fuse wire is blown, and means for providing a visual indication thereof. 
     
     
       17. The apparatus of claim 16 wherein the visual indication means includes a pair of LED one of which is conducting and the other of which is non-conducting, and a switching circuit for switching the LED which is conducting to its non-conducting state, and the LED which is non-conducting to its conducting state, when a semiconductor is destroyed or a fuse is blown to provide a visual indication of the occurrence. 
     
     
       18. The apparatus of claim 17 wherein said switching circuit includes a plurality of transistors, one of which controls switching of one of the LED, a second of which controls switching of the other LED, and a third of which is responsive to the opto-isolators to switch the conducting states of said first said and second transistors, thereby to switch the operating states of the LED. 
     
     
       19. The apparatus of claim 18 wherein said visual indication means further includes a relay operable by one of said transistors when the operating states of said LEDs are switched to provide an indication to a remote location of the occurrence. 
     
     
       20. A transient voltage surge suppressor for use on a single or poly-phase power distribution network to protect equipment supplied power from the network from damage caused by line surges or transients comprising: a plurality of surge suppression assemblies each of which includes a plurality of semiconductors connected in parallel and a fuse wire connected in series with each semiconductor, each surge suppression assembly being mounted on a separate circuit board, and a surge suppression assembly being connected between the "phases";   fault detection means including means for sensing when a semiconductor in one of the surge suppression assemblies fails, or when a fuse wire in one of the assemblies blows, and means for providing a visual indication thereof, said fault detection means being mounted on a circuit board separate from the other said circuit boards,   a module in which the respective circuit boards are installed, the circuit boards on which said surge suppression assemblies are mounted being installed parallel with each other, and the circuit board on which said fault detection means is mounted being installed at an angle thereto; and,   plasma suppression means for preventing spread of a plasma produced when a semiconductor fails or a fuse wire clears, said plasma suppression means including a sand with which the module is filled thereby to substantially completely fill the spaces between the circuit boards on which the surge suppression means are mounted, and an epoxy material with which any remaining space in the module is filled alter the sand is poured into the spaces between said circuit boards and after said circuit board on which said fault detection means is mounted is installed in the module.